1. Field of the Invention
The invention relates to endo-6-hydroxybicyclo[2.2.1]heptane-endo-2-methanol, its derivatives and a process for its preparation.
2. Description of the Prior Art
The endo isomers of this invention are known compounds. However, the known processes for preparing these endo isomers are not stereo-specific and yield a mixture of endo and exo isomers. For example Brit. Pat. No. 1,011,318 teaches a process for the production of a mixture of 2- and 3-hydroxybicyclo-[2,2,1]-heptane-6-methanol by adding water to the olefinic double bond in bicyclo-[2,2,1]-heptenemethanol-(6). Fr. Pat. No. 1,434,574 teaches a process for preparing a mixture of 2-hydroxymethyl-5(6)-hydroxybicyclo-[2,2,1]-heptanes by reacting 2-hydroxymethybicyclo-[2,2,1]-heptene-(5) at a temperature between 100.degree. C. and 180.degree. C. and at atmospheric or superatmospheric pressure in the presence of a Lewis acid with an excess of a C.sub.1 -C.sub.4 aliphatic monocarboxylic acid and then transesterifying the resultant diester using a monohydric aliphatic alcohol in the presence of a basic catalyst. French Addition No. 87,991 to Fr. Pat. No. 1,434,574 teaches another process for obtaining the same product mixture of Fr. Pat. No. 1,434,574, the process comprising refluxing 2-(hydroxymethyl)bicyclo[2.2.1]hept-5-ene with anhydrous acetic acid and boron trifluoride in ethyl ether for 5 hours and then heating the reaction mixture in a pressure vessel for an additional 5 hours at 150.degree. C. Acetic acid is removed in vacuo to yield 2-(acetoxymethyl)-5(6)-acetoxybicyclo[2.2.1]heptane which is subsequently hydrolyzed to yield the mixture of hydroxy-substituted bicyclo[2.2.1]heptanes. The mixtures produced by these illustrative processes include both positional (5- and 6-hydroxy) and stereo (endo and exo) isomers. These mixtures have proven utility in the preparation of polycarbonates (Brit. Pat. No. 1,042,200) and polyurethanes (Brit. Pat. No. 1,011,318).